Real bias

I have had arguments with numerous friends and family about the reliability of Fox News.  They claim that it is a propaganda machine for the political right.  I acknowledge that fact but point out that the rest of the mainstream media is a propaganda machine for the political left and that Fox is, in fact, more balanced than the rest.  At this point the discussion generally ends with claims that fall somewhere along the lines of "you really are paranoid, don't be ridiculous, the networks are the model of unbiased journalism".

Well, PEW, not known as a conservative outfit, recently did some analysis of the recent election and found that MSNBC (NBC's political news channel) ran stories on Romney at a ratio of about 24:1 negative to positive.  Fox News, on the other hand, ran stories on Obama at a ratio of about 6:1 negative to positive.

So who's more biased?

Note: I haven't been able to find similar information on CNN for this election but I did stumble across a similar analysis for the last election.  Quick results (McCain 61:13 and Obama 39:36).  Slightly more balanced than Fox (at least when we compare two different elections) but definitely tilted to the left.